Torque Converter Clutch Question.

[George7941]

I don't have much experience with auto transmissions, every vehicle I have ever owned have had manual transmissions.

I was driving my friend's 2006 Chrysler 300 3.5lV6 today. On the highway, on level ground, cruising at 100kph(62mph),the engine spinning at roughly 2000rpm, I noticed that if I opened the throttle a bit, the tach would go up to 2500rpm within a second with very little change on the speedo. This should not be happening if the TCC was engaged. Does this mean that there is some problem with the TCC on this car and it needs to be looked into?

 

[yonyon]

I think it's more likely the PCM is unlocking the TCC when you press the accelerator down in preparation for some acceleration.

 

[oggb]

Many transmissions will unlock the torque converter based on calculated load, TPS, transmission fluid temperature, RPM, etc.

 

[The_Eric]

Originally Posted By: yonyon
I think it's more likely the PCM is unlocking the TCC when you press the accelerator down in preparation for some acceleration.


This.

Originally Posted By: JRed
Many transmissions will unlock the torque converter based on calculated load, TPS, transmission fluid temperature, RPM, etc.


And this...

 

[yonyon]

Originally Posted By: JRed
Many transmissions will unlock the torque converter based on calculated load, TPS, transmission fluid temperature, RPM, etc.



You make it sound almost like there's some sort of computer doing this. Everybody knows automatic transmissions are actually captured specimens of an alien species that Chrysler and Allison have pressed into slavery. There's no calculated whatsits and whatnot involved at all. Your propagaganda in support of the alien menace is completely transparent.

 

[Colt45ws]

Woah! I always thought its was a wizard that magic'd it!

On topic, yes its being unlocked intentionally. Many are also setup to unlock when you lift off the throttle. Really annoying. You can hear the engine flare a bit before it locks up again.

 

[antonmnster]

I hate hate hate the lock/unlock madness in my BMW. It's just salt of in the wound of having bought an automatic in the first place. It's totally impossible to keep the revs from wandering up and down like a motorboat and the engine doesn't feel connected to anything other than a pile of Jello.

I just hope it dies soon so I can swap a 5 or 6-speed in.

 

[SteveSRT8]

Originally Posted By: George7941
I don't have much experience with auto transmissions, every vehicle I have ever owned have had manual transmissions.

I was driving my friend's 2006 Chrysler 300 3.5lV6 today. On the highway, on level ground, cruising at 100kph(62mph),the engine spinning at roughly 2000rpm, I noticed that if I opened the throttle a bit, the tach would go up to 2500rpm within a second with very little change on the speedo. This should not be happening if the TCC was engaged. Does this mean that there is some problem with the TCC on this car and it needs to be looked into?


Many of the 3.5 V-6 models have the NAG1 which is really a WA580 Mercedes design built by Chrysler in Indiana.

Fantastic gearbox, a bit dated now but WAYYYY ahead of its time.

One of its coolest features is infinitely variable lockup. No on/off, just smooth infinitely variable lock in every gear but first and reverse.

 

[mechtech2]

Sounds perfectly normal. The lock up is unlocked for passing power.

 

[eljefino]

The best part of the saturn s-series automatic programming is how one can get about half throttle or even more going up hill before it unlocks the TC. In fact it will usually go from 3rd (unlocked) to 4th, locked, in one move.

I consider it an automatic for the stick shift driver. But I'm one of those old-school types who thinks 4 speeds is just right, and expect shifting on my schedule. These newer cars with PWM clutches bug me just because I like feeling a reassuring little thump.

 

[rslifkin]

^ That's about the same as the auto in the Jeep. Yeah, it's still a slushbox, but it's pretty good at not annoying the driver. And an auto that's willing to lug hard in lockup is pretty nice.

 

[SteveSRT8]

You haven't seen lugging till you've seen my car turn a corner at 1100 rpm in 4th gear!

It's absolutely hilarious to watch the programming trying to save gas in a 425 hp car.

 

[rslifkin]

Heh. Mine's just about that bad once you're going fast enough for 4th gear and TC lockup. I can get to about 40-50% throttle without a downshift with it lugging along in 4th with the TC locked at 1100 rpm, and it just pulls.

 

[CBR.worm]

Originally Posted By: SteveSRT8
You haven't seen lugging till you've seen my car turn a corner at 1100 rpm in 4th gear!

It's absolutely hilarious to watch the programming trying to save gas in a 425 hp car.


Yeah, some of the new Infiniti's are pretty crazy transmission programming wise as well. I think they are 7 speeds now? The last FX50 I test drove was upshifting faster than I could push the pedal down in normal traffic, it was holding the RPM below 1,500 with moderate throttle, felt like it was forcing it through the gears unnaturally fast. Just a hair more throttle and suddenly it would stay 2 or 3 gears lower. Makes my FX45's old 5 speed auto feel like a real slush box. Mine rarely drops below 2,400 unless you are really light on the throttle and the torque converter only locks in 5th and unlocks over about 20% throttle. Not really ideal for anything.

When I am towing my trailer on the highway I keep track of the TC being locked or not. at 80mph (3,000rpm w/ it locked) it may or may not lock in 5th, if it doesn't lock I back off a hair to let it lock and maintain as much speed as I can while keeping it locked. I assume that having it unlocked for hundreds of miles at 80 would probably create a little excess heat.

 

[Kiwi_ME]

Originally Posted By: CBR.worm
... I keep track of the TC being locked or not...
A temp gauge on the outside of the oil line to the cooler is a great way to get near real-time feed back on the lockup status. Even one of those cheap Bordon tube coolant temp gauges works fine. On my '00 Xterra I'd see 1 deg F per second increase the moment it let go in top gear. Hit the OD-off switch to drop it to 3rd where the TC will immediately lock again.